Tor Harold Percival Bergeron1 Helmut K. Weickmann 2

Dedication on the occasion of presenting the Eleventh Award of the International Meteorological Organization Prize, 1966, to Professor Bergeron: "In recognition of his Outstanding Contributions to Air Mass Analysis, Physics of and Theory of Fronts, His Furtherance of Inter- national Co-operation in the Science of the Atmosphere; and his Stimulation of the Develop- ment of the Science of by his Lectures and Writings". In the name of The World Meteorological Organization—A. Nyberg, President.

The ethics of the medical profession was given a clear log. No doubt it must have been this interest in the ever direction some 2500 years ago by the famous oath of changing which sharpened his natural gift for Hippocrates. No similar definition exists for the ethics observation and developed his inclination to systema- of natural scientists in pursuing their profession. This tize and categorize. It must be considered as one of the may be part of the reason that the pursuit of scientific lucky circumstances in the development of the new sci- research in the natural sciences, and particularly in the ence of meteorology that Bergeron, after finishing Uni- physical sciences, has often met with suspicion and even versity training in 1916, joined the group of young hostility. Indeed, the precarious situation in which we scientists around Vilhelm Bjerknes, who, coming from find basic research today may be a direct consequence theoretical fluid mechanics, had conceived the idea of of its tremendous advances. Scientific research rather air masses, air mass boundaries, and fronts in order to than technological development is blamed for the explain natural weather phenomena. Bergeron's keen atomic bomb, for air pollution, for the deadly accuracy gift of observation, trained and refined since his youth, of missiles over thousands of miles. There are, however, was as important a contribution to the pioneering other shortcomings which we find in the backyard of "School of Bergen" as was Bjerknes' ingenious theoreti- our own science, the science of meteorology. For almost cal analysis in the development of his "Polar Front 30 years, we have promised weather modification: Theory". during droughts, or no hail during the hail season, Figures 1 and 2 show what had been accomplished in but all we have done is to invent or apply new methods weather analysis in a few years. It is the case of 10—13 of statistics in order to prove that nature behaved as we October 1923, which is the development of a powerful wanted her to behave, while hail and droughts con- "Skagerrak" storm cyclone. This study was accomplished tinued. Now, we find that statistics fail us, too, and is at the Geophysical Institute of the University of Leipzig no panacea at all. Moreover, the costlier the means that jointly by Tor Bergeron and G. Swoboda. It was pub- we have needed or wanted for our research, the more lished in 1924. The authors call attention to the huge exaggerated our promises have become: the attainment precipitation area of about 1700 km in length and an of forecasts accurate for two weeks could be achieved average width of 250 km. They take notice that this rain with another and bigger computer. area is nearly parallel to the isobars and shows relatively Apparently, there can be but one ethical motivation weak cyclonic convergence. This caused most weather for research in the natural sciences that would corre- services to miss the correct forecast. The authors point spond to the oath of Hippocrates: namely, to conduct out that convergence appeared in change of wind speed research in order to find the truth. As simple as this rather than in change of wind direction. A painstaking may sound, it is difficult to achieve. The man to whose analysis of the hydrometeors did tell something about memory this lecture is devoted has been a shining ex- the air masses and weather processes within them: rain ample of a scientist in search of the truth and his publi- was indicated in three different intensities; fog and haze cations testify on almost every page, his continuous had special symbols and so had various types of shower struggle with nature's complexity in search of the truth. clouds whose symbol appears in three different types: Tor Bergeron was born in England on 15 August one as a regular triangle as we use it today, one as a 1891. While he was still a child, his family returned to triangle sloped to the left, and one as a triangle sloping , their home. As a schoolboy, he had already dis- to the right. covered his interest in weather and particularly clouds. Years of intensive research followed, which culminated He began at an early age to keep a detailed weather in 1928 in Bergeron's fundamental dissertation "Uber die drei-dimensional verkniipfende wetteranalyse". The 1 This lecture was delivered by the author at the Annual key word in the title is "drei-dimensional" (3- Physics and Atmospheric Electricity Conference in dimensional), as the thesis expressed the need for aero- Issaquah, Wash, on 2 August 1978. The author was given the logical analysis, in contrast to the analysis of fronts, Distinguished Lecturer Award by the American Meteorologi- cal Society for his presentation of this paper. which belonged to the lower atmospheric layers. Already 2 Atmospheric Physics and Chemistry Laboratory, Environ- in the introduction, Bergeron foresees and discusses the mental Research Laboratories, NOAA, Boulder, Colo. 80303. schism that should determine meteorologic research for 0003-0007 / 79/ 050406-09$06.25 the next decade: Is weather determined by "steering © 1979 American Meteorological Society processes" near the stratosphere or by frontal develop-

406 Vol. 60, No. 5, May 1979 Bulletin American Meteorological Society 407

FIG. 1. Analysis of development of Skagerrak Cyclone 10 October 18 GMT.

between dense and compact water clouds with layers of permanent ice nuclei a main source for all normal, i.e., large-drop-, graupel and hail and the common flakes . . . shortly all forms of precipitation with the exception of drizzle and its solid counterpart, the 'diamond dust'. Consequently, it is assumed that the first-named forms originate in our latitudes in a high ice cloud." 3 Tor Bergeron, 15 August 1891-13 June 1977. Bergeron was a personality with many gifts, one of which was the gift of languages. Many of his papers are ments near the surface? The basic idea of this publication written in German, but he also was fluent in Russian, was to confirm the Polar Front theory of the Bergen in English, in French, and Latin, etc. In 1938, he edited School, and to show that the weather analysis for the a meteorological dictionary in six languages for F. dailv weather forecast has to do with the definition of Linke's Tachenbuch. One of the coauthors is Vera cold and warm air masses on the basis of certain char- Romanov-skaja-Bergeron. Vera used to be a student of acteristic properties that would not change or "age" as meteorology in Moscow and was in charge of inviting the air masses continue flowing across oceans and conti- Bergeron to the Moscow University for a series of nents. An air mass can be related to certain weather lectures. This stay became most decisive for Bergeron's types; and therefore, the air mass analysis is important and Vera's life as Vera became not only his wife but his for weather prediction. Moreover, air masses can flow scientific assistant and secretary as well. In Moscow, he side by side or against each other, thus producing air found numerous new friends, one of them Professor mass boundaries, or fronts, along which cyclogenesis S. P. Chromov, who published several books based upon can occur. Bergeron defined as one of the important air Bergeron's lectures, most notably, in 1934, the book mass characteristics the turbidity or opalescence of the Einfiihrung in die synoptische Analyse. Bergeron not air mass and he developed an observational system that only spoke foreign languages fluently, but he knew all includes visibility, contrast, and sky color for recognizing the grammatical rules and regulations and he usually whether an air mass is polar or tropical. It is fascinating knew them better than you, yourself, in your own mother to follow his struggles to reconcile events occurring on tongue. This gift enabled him to travel and to lecture the large scale with his observations which are limited in foreign countries such as Germany, Russia and Yugo- to meso- and microscale, the scale with which he was slavia. His "Sprachgefuehl" (feeling for the correct ver- familiar from his cloud and hydrometeor observations. bal expression) led him, for instance, to suggest that His cloud observations led him to the concept of the "orographic" was the wrong word if one discussed oro- role of ice crystals in water clouds and to their im- graphic precipitation effects because what one really portance for precipitation processes. These ideas were meant was oreigenic precipitation effects. Rain could already contained in his dissertation; therefore, the year only be "oreigenic" (caused by orography). 1928 is given by him as the year in which he conceived It is interesting to note that his precipitation theory his famous precipitation theory, and not the year 1933 was an outgrowth of his gift of observation. It dates in which he proposed his theory to the IUGG assembly in Lisbon, Portugal. Indeed we read on page 31 of his 3 Translated from the original German text by the present dissertation: "The author recognizes in the interaction author.